Hydraulic jack



Nov. 13, 1951 l. M. WHITE 2,5 75,308

HYDRAULIC 4JACK Filed Aug. 5, 1946 1N VEN TOR. /e/q Mofa/4N M/f-f/rf BYZPatented Nov. 13, `v1951 UNITED STATES PATENT v( )FFICIE ApplicationAugust 5, 1946, SerialNo. 688,498

8 Claims. (Cl. 60-51) My invention relates to means especially designedfor use in connection with deep well reciprocating pumps for the purposeof operating the pump rod to discharge pumped fluid from the well.Devices of this nature have come into use in deep petroleum wells inwhich it is necessary to supply a pumping structure of considerablecapacity capable of operating at relatively high pressures. There iscustomarily employed a pumping jack including a cylinder having areciprocating piston therein. The cylinder is periodically supplied withhydraulic fluid, such as oil, from a storage tank through the medium ofan actuating pump and is alternately deprived of oil by the pump, theoil being returned to the storage tank. To secure a partial balance ofthe reciprocating parts the storage tank customarily is closed and isprovided with an air cushion operating at a suitable pressure so thatthe load on the oil pump is approximately constant. It has been found inpractice that the air cushion tends to become depleted due`to loss ofair from various causes.

It is therefore an object of my invention to provide in a hydraulic jackmechanism a means for maintaining a suitable body of air in thebalancing tank.

It is another object of my invention to provide a hydraulic jack inwhich the pressure air supply is automatic.

A further object of the invention is to provide a hydraulic jack inwhich the air supply can readily be adapted to mechanism alreadyavailable in the hydraulic jack assembly.

A further object of the invention is to provide in a hydraulic jack anair supplying structure capable of regulating the supplied air pressure.

An additional object of the invention is to provide a hydraulic jack ofa generally improved character.

Other objects together with the foregoing are attained in the embodimentof the invention disclosed in the accompanying drawing, in which theligure is a diagrammatic disclosure of the hydraulic jack of myinvention, incorporating the air supplying means therein.

While the hydraulic jack of my invention is susceptible to utilizationin a number of different environments and is capable of variationdepending upon various operating characteristics, it has successfullybeen embodied as -shown in the accompanying diagram. Some of thestructures diagrammed are more fully illustrated in the patent of FredH. Rued, 2,481,623, issued September 13, 1949, and entitledv PumpingJack. The

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mechanism includes a main jack cylinder 6 usually installed verticallyover a well to be pumped and serving as a housing for a reciprocablepiston 'I, secured to the end of a rod 8 connected to the sucker rod ofa deep well pump. A suitable amount of oil under appropriate pressure issupplied to or withdrawn from the cylinder 6 beneath the piston 'Ithrough a lower port 9 and a connecting conduit I I extending to a portI2 in a main valve, generally designated I3. The main valve I3 isprimarily a cylindrical housing having a number of different ports andpassages therein and containing a valve shuttle I4. Incorporated in thevalve shuttle is a central spindle I6 and a valve head I'I, in oneposition of the Valve disposed to one side'of theport I2, and a similarvalve head I8 Vin that positionv of the valve dis-v posed on the otherside of the port I2. A head i9 comparable to the head I'I is in thispositionv of the valve disposed adjacent one end of the valve housing.

The arrangement of the port I2, with respect to the heads I'I and I8-and also with respect to an inlet port 2| is such that, in theillustrated position of the valve, oil from a suitably driven main pump22 is discharged into the cylinder 6. The oil is received bythe pump 22from a balancing tank 23 through a conduit 24 'and through ports 26 and21 disposed inV this position of the valve between the heads I8 and I 9and through-a conduit 28 to a pump inlet pipe 29. Thus oil from thebalancing tank 23 is drawn by the pump 22 through the control valve I3and is then forced again through the control valve into the jackcylinder E, so that during the operation of the pump under thesecircumstances oil under pressure is supplied beneath the piston 'I andthe rod 8 is lifted. b

The lifting action of the piston I continues until the piston hasoverridden a selected one of a plurality of ports 3I, 32, 33 and 34 inthe cylinder 8. The effective one 33 of such ports is connected througha rotary selector valve 36 and through a check valve 31, aiiording iiowin the directionv of the arrow, to a conduit 38,extending to a pilot"valve. A"

The pilot` valve is primarily a body 39 having a cylindricalbore-'within whichop'erates' a shuttle'- 4I having a central stem 42'Sat one end of which'.v a head 43 is disposed. Pressure' from theconduit 38 acts through a port I4-upon the head Y43 and tends totranslate the shuttleY 4I to the'right in' the figure. This pressure isin part opposed by* pressure upon a head 46 atv the end of the stem 42.The head 46 slides withina=`chamber 4'I-forining 1:

an extension of the valve body 39 and connected by a conduit 48 to theinterior of the balancing tank 23. The body 49 of oil in the tank iseiective to transmit the interior tank pressure through the conduit 48against the head 46 to oppose the pressure upon the head 43. Leakagepast the head 46 discharges through a port 5| into a conduit 52 leadingto a sump 53 opento atmospheric pressure. Leakage past the head 43discharges through a port 54 into a line 56 likewise leading to the sump53. Due to the fact that the diam' eter of the head 43 is much greaterthan that 0f the head 46, whereas the unit pressure acting against bothheads is approximately the same, there is a resultant unbalancedpressure effective under the described conditions to move the shuttle 4|to the right, as seen in the figure. When such motion is accomplished,the shuttle 4I is shifted so that the head 46, the head 43, and anintermediate head 51 are all moved to the opposite extreme position. Thehead 51 then lies on the right side of a pressure line 58 extending tothe valve body 39 from a scavenge pump 59 suitably operated from amotor(not shown).

The scavenge pump withdraws hydraulic fluid from the sump 53 through anintake duct 6I. From the discharge conduit 58 a by-pass line 62 leads toa relief valve 63 closed normally by a spring 64. The valve 63 is openedby a pressure in excess of a predetermined pressure to permit flow fromthe conduit 62 through the valve 63 and through a return conduit 66 tothe sump 53. With this arrangement when the pressure is excessive thescavenge pump 59 is effective merely to circulate the excess pressureVoil locally from the sump through the pump but when the pressure isless than a predetermined amount the scavenge pump discharges onlythrough the line 58 into the interior of'the pilot valve body 39 througha port 61. When the head 51'is on the right hand side of such port thepressure fluid then iiovvs from the'pilot valve body 39 through adischarge port 68 into a conduit 69 leading to a port 1I in one end ofthe body of the main valve I3. Thus the end of the head i9 is exposed tothe scavenge pump pressure. The main valve shuttle I4 is substantiallyunbalanced as its opposite head I1 is provided with a discharge port 12leading through a conduit 13 back to a port 14 in the pilot valve body39. v

When the pilot valve shuttle is in a position opposite rto that shown,iiow from the conduit 13 is then through the body 39 from a port 18therein and through a short line 11 into the discharge conduit 52leading back to the sump 53. Because ofthe unbalanced pressure existingon the main valve shuttle I4 it is translated from the position shown inthe figure to a position in the other extreme end of the valve body.Thus, when the piston 1 overruns the port 33 there is produced atranslation-of the shuttle 4| which in turn produces a correspondingtranslation of the main valve shuttle I4. When this occurs the head I8changes sides and occupies the left side of the pump discharge port 2|.Flow is then from the main pump 22 through the outlet port 26 and theline 24 back into the pressureA tank 49. Simultaneously the QQndult Hisconnected through the port I2 and an outlet "port 18 in the body oi themain valve I3 so that oil flows from the cylinder 6 through the mainvalve cody and port 18 and through a conduit 19 to the pump inletconduit 29 for return to the balancing tank 49.

Asl the piston 1 descends,y the space above it is substantially atatmospheric pressure, This $01,3-

dition persists until the piston 1 has lowered sufciently to uncover acontrol line 8| having a suitable check 82 therein and communicatingwith the line 38. When the line 38 is thus exposed to atmosphericpressure, ow to relieve the pressure in the line 38 takes place throughthe check 82. The pressure exerted on the head 43 is thus droppedapproximately to atmospheric. The pressure on the smaller head 46 isstill considerably above atmospheric. as the head is exposed through theconnection 48 with the balancing tank pressure. The unbalanced pressureshifts the pilot shuttle 4I back into the position shown in the iigure.Consequently flow from the scavenge pump 59 goes through the port 61 andthrough the pilot valve body 39 to discharge from the port 14 throughthe line 13 into the body of the main valve I3. The head I1 is thusexposed to the scavenge pump pressure While at the same time thepressure on the opposite head I9 or the main valve is reducedapproximately to atmospheric. This is because pressure com` municationis through the port 1I and the line 69 and the ports 68 and 54 in thepilot valve with the discharge line 56 leading to the sump 53. Thedescribed cycle is repeated indefinitely un der control by the motion ofthe piston 1 within the cylinder 6 in turn affecting the motion of theshuttle 4I. This in turn aifects the operation of the main valve I3,itself controlling the supply of oil from the balancing tank 49 to thecylinder 6- and the return of oil from the cylinder to the balancingtank.

During operation it is one of the functions ofl the scavenging pump 59to return excess oil to the balancingtank 23 and to maintain a suitablelevel of oil for operation within the sump 53. For this reasonsubstantially all of the leak age or drainage oil is led back to thesump 53 butthat may not be suiiicient to provide adequate oil for thesump. A make-up means is provided.

When the pilot shuttle 4I is translated to the-- opposite position fromthat illustrated in the gure, the scavenging pump discharges through itsconduit 58 and the port 61 and then through the port 68 and the conduit69 into the body of the main valve I 3. If the main valve is displacedfrom the position shown in the gure, oil ows from the port 1I throughthe end'chamber i the body to an outlet port 83 leading into aV line 84.This line leads to a valve -86 controlled by a iioat 81 responsive tothev level of oil in the sump 53 and governing dow through a pipe 88into the sump. If the sump level is low the scavenge pump is effectivelocally to circulate oil and to pump it back into the sump 53. Whenthere has been suiiicient leakage and the sump level is correspondinglyhigh, the valve 86 is closed and uid in the conduit 84 then flowsthrough a branch pipe 89 leading through a check 9| into the balancingtank 23 which also serves as a reservoir.

In accordance with my invention the fluiddis charged by the scavengepump is utilized to actu.- ate a means for `supplying make up airtothe.- When the pilot. valves in.

balancing tank 23. the position shown in the gure, the scavenge "twopaths. It can proceed through a port l94 connected by a conduit 96 to avalve 91.' This .valve is normally closedgby a spring 98 yet is openedupon the occurrence of an excessive pressure or one higher than apredetermined pressure to permit the passage of oil throughvthe valveand through a, duct 99 back into the sump 53. The pressure at which thevalve 91 .opens is less than that at which the relief 63 opens. Iftherefore the pressure of the oil in the line 13 or its connections isexcessive when the main valve is translated as shown, the excess oil cantravel through the conduit 96 and by opening the valve 91 can escape toatmospheric pressure through the conduit 99 into the sump 53. When the'pressure is below a set or predetermined value, this avenue of egressis closed by the valve 91' and only the alternative path can beutilized. The amount of flow through the alternative path is small andis more in the nature of a pulse.

The alternative path includes a port |0I leading from the main valvebody I3 through a conduit |02 merging with a pipe |03 adjacent the checkvalve 93. The conduit |03 extends to an air compressor |04. Thestructure of this air compressor can be varied to suit individualcircumstances, but in the present instance it comprises a main cylinderbody |06 within which is disposed a reciprocable plunger |01 having anenlarged piston |00 thereon exposed to the pressure of oil enteringthrough the conduit |03. Likewise included in the plunger is a reduceddiameter portion |09 designed to reciprocate within a reduced cylinderIII. Between the enlarged and the reduced cylinder portions there isformed a variable chamber |I2, connected by a pipe ||3 to the air spaceI I4 within the balancing tank 23. When the pressure within the chamber|06 is in excess of the resultant pressure on the other side of the head|08, plus the pressure on the plunger |09, the plunger is translatedupwardly as seen in the iigure. When the pressure within the chamber |06is low, tank pressure within the chamber I I2 is eifective to translatethe plunger downwardly as seen in the figure. The extension |09 servesas an air pump. In its lowermost position it uncovers an air port |I6communicating through a duct |I1 and a check valve |I8 to theatmosphere. The cylinder II I is provided with a check valve I9controlling flow from the cylinder through a duct |2| into the air spaceII 4.

Fluid under pressure from the scavenge pump 59 flows through the pipe 13and the pipe |02 into the conduit |03 and lifts the plunger piston |08.The rising piston cuts off the port ||6 thus trapping a body of air andduring its further motion compresses the trapped air sufficiently tounseat the outlet check II9 and to displace the air into the chamber II4. This position of the plunger is maintained until such time as themain valve shuttle I4 is translated to the opposite extreme positionfrom that shown in the figure and has cut off the port IOI. The shift ofthe shuttle I4 is caused by a shift of the pilot valve shuttle 4|connecting the port 14 with the port 16.- Since the'latter is connectedby the conduit 52 to the atmospheric pressure sump 63, the pressureWithin the conduit 13 likewise drops substantially to atmospheric. Underthese circumstances the intermediate pressure from the chamber II4 isexerted to close the check valve I I9 and is effective upon the.differential area between the head `|08 and the portion |09 to force theplunger |01 downwardly. This motion discharges the oil previouslycontained in the cylinder |06 through the conduit |03 and past the checkvalve 93 into the connecting pipe 92 and so into the conduit 13 andfinally back to the sump. Having returned to its" lowermost position,the air pump plunger |01 de--` riving its power from the scavenging pump53 is set for a repetition of the cycle of operation in response to theoperation of the main valve |3 and oi the pilot valve. The pressure ofthe air in the chamber I I4 is regulated by the pressure at which thevalve 91 is forced open by the actuating liquid.

I have thus provided in accordance With my invention in a hydraulic jacksystem including a main cylinder, a balancing tank, a main valve and ascavenging pump, a means for supplying make up air to the balancingtank, the make up' air supply means being governed and actuated by thescavenge fluid and the pressure of the air being regulated in accordancewith any set or desired value. The structure of the air pump is a typewhich can be readily incorporated with previously existipg hydraulicjacks since it relies upon a hydraulic drive readily provided by theinstallation of appropriate conduits and pipes. There is afforded by myinvention an improved airsupply for a hydraulic pumping jack mechanism.

I claim:

1. In a hydraulic jack having a balancing tank for containing air andoil, a main pump, a control valve for governing oil now to and from saidtank through said main pump, and a scavenge pump for periodicallydischarging oil into said tank under control of said valve, thecombination of an air compressor cylinder communicating with theatmosphere and with said tank, check valves for said cylinder, a plungerin said cylinder, and means responsive to the operation.

of said control valve for alternately subjecting an actuating surface ofsaid plunger to the pressure of oil discharged by said scavenge pump andto atmospheric pressure.

2. In a hydraulic jack having a balancing tank for containing air andoil, a main pump, a control valve for governing oil flow to and fromsaid tank through said main pump, and a scavenge pump for dischargingoil into said tank under control of said valve, the combination of anair compressor communicating with the atmosphere and with said tank,means for utilizing oil discharged from said scavenge pump to drive saidcompressor, and means responsive to the operation of said control valvefor controlling said utilizing means.

3. In a hydraulic jack having a balancing tank for containing air andoil, a main pump, acontrol valve for governing oil flow to and from saidtank through said main pump, and a scavenge pump for discharging oilinto said tank under control of said valve, the. combination of an aircompressor discharging into said tank, means including said scavengepump for driving said air compressor, and-means responsive to theoperation of said control valve for controlling said driving means.

4. In a hydraulic ,jack having a balancing tank for containing air andoil, a main pump, a main control valve for governing oil flow to andfrom said tank through said main pump, and a pilot valve for operatingsaid main valve, the combination of an air compressor discharging intosaid tank, a secondary pump for driving said air compressor, and meansresponsive to the operation of said pilot valve for controlling thedriving of said compressor by said secondary pump.

5. `lin-.a hydraulic `lack having a balancing tank for containing airand oil, a control valve for governing -oil flow to and from said tank,and 'a scavenge pump for discharging oil into said tank under control ofsaid valve, the combination of an air compressor for supplying air tosaid tank, means for utilizing oil discharged from said scav enge pumpto drive said compressor, means responsive to the operation of saidcontrol valve for controlling said utilizing means, andnieans responsiveto the pressure of oil discharged from said scavenge pump in excess of apredetermined value for rendering said supplying means inoperative. 6.In a hydraulic jack having a balancing tank for containing air and oil,an atmospheric pressure #anhand a scavenge pump `for dischargingoil fromsaid atmospheric pressure tank into said balancing tank, the combinationof an `air compressor for supplying air to said balancing tank, meansfor utilizing oil discharged from said scavenge pump to drive saidcompressor, and means responsive to the pressure of said discharged oilin excess of a predetermined value for renderli?,F said supplying meansinoperative.

7. In a hydraulic jack having a cylinder with a port therein, a pistonreciprocable in said cylinder to cover and uncover said port, abalancing tank foi-.containing air and oil, a main pump, a control valveconnected to said port for governing oil iiow to and from said cylinderand to and from said tank through said main pump, and a scavenge pumpfor discharging oil into said tank under-control of Said valve, thecombination .of an air compressor discharging into said tank. meansincluding said scavenge pump for driving said air compressor, and meansresponsive to the operation of said control valve vfor controlling saiddriving means,

8. In a hydraulic jack having a cylinder with a port therein, a pistonreciprocable in said cylinder to cover and uncover said port, abalancing tank for containing air and oil, a main pump, a main controlvalve lfor governing oil flow to and from'said cylinder and, to and fromsaid tank through said main pump, and a pilot valve con nected to saidport for operating said main valve, thecombination of an air compressordischarge ing rinto said tank, a secondary pump for .drin ing said aircompressor. and means responsive to the operation of said pilot valvefor controlling the driving of said compressor by said secondary pump.

IRA MORGAN WHITE.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 1,879,262 Hubbard Sept. 27, 19321,941,766 Thom Jan. 2 193i 2,157,219 Salentino May 9, 1939 2,343,302`Twyman Apr. 25, 1944 2,414,979 Ross Jan. 28, 1941

